<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>javascript</title>
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box
    }
    body {
      font-size: 14px;
      padding: 20px;
    }
    ul li {
      line-height: 30px;
    }
  </style>
</head>
<body>
    <div id="dom">123</div>
  <ul>
    <li>
    </li>
  </ul>
</body>
<script>
    const li = document.querySelector('li');
    let sc = document.createElement('script')
    sc.textContent = "document.querySelector('#dom').innerHTML = '9999'"
    li.innerText = '1121&lt;script&gt;console.log(2)&lt;/script&gt;1212'
</script>
</html>